Electric switch



Oct. 10, 1933. I PHELAN 1,929,606

ELECTRIC SWITCH Original Filed Dec. 1925 1/11/1114 IIIIAII Patented Oct. 10, 1933 UNITED STATES ELECTRIC SWITCH Louis A. M. Phelan, Chicago, 111., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Original application December 17, 1925, Serial No. 75,895, now Patent No. 1,847,037, dated February 23, 1932.

9 Claims.

My invention relates to electric switches and it has special reference to operating mechanisms therefor that serve to open and close associated electric circuits in accordance with external thermal conditions which influence the operating mechanism.-

This is a division of my copending patent application Serial No. 75,895, filed December 17, 1925.

One object of my invention is to provide an operating mechanism for a mercury contactor that is tilted by means of an operating element or actuator subjected to the influence of thermal conditions.

One specific application of my present invention relates to its use as a stack thermostatic switch and in such relation I shall describe it. As the operating element or actuator is disposed within the stack and under direct influence of the thermal conditions of the furnace or the like, there has existed marked difficulty in keeping the operating element or actuator free from the products of combustion given off from the substance burned to create this thermal condition. Deposits of the products of combustion on the operation element or actuator are detrimental to its operation; therefore a further object of the present invention is to minimize the extent of these deposits.

Tiltable mercury switches or contactors are used predominately where a very small quantity of energy is available for actuating purposes because only a very slight tilting movement is necessary to effect a change of electrical circuit connections. Since it is impossible to insure the cessation of the actuating force at the same time that the limits of the switch or contactor movements have been reached, it is apparent that some provision must be made whereby the actuator may move through a greater range. This relative movement between the actuator and the contactor in my present invention is dependent upon a frictional engagement between them as will be hereinafter described.

Another feature of the switch is its adaptability to be installed on the various types of stacks in present day use. The stacks usually have inclined surfaces on which the device is positioned and as it is usually desirable to mount the contactor and its casing in a substantially vertical plane, means are provided to compensate for any angularity beatuween the planes of the switch and the stack w For a better understanding of the nature, scope and characteristics of my invention. reference Divided and this application February 17, 1932.

Serial No. 593,482

may be had to the accompanying drawing in which- Figure 1 is a front view of an electrical switch mechanism embodying one form of my invention with the cover of the casing removed;

Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1; and

Fig. 3 is an enlarged detail view showing the means for establishing frictional engagement between the actuator and the contactor.

Referring more particularly to the drawing, the switch comprises a casing 10 having a cover 11 secured thereto by means of screws 12. An aperture is provided in the back wall of the casing through which projects a bearing member 13 secured to the casing upon which bearing member is secured a tube 14 which projects a short distance into the stack 15. The tube 14 has an aperture 16 which is disposed on the outside of the stack to afford a proper ventilation therethrough.

Within the stack and in axial alignment with the tube is disposed a helical bimetallic element 1'7 which is fixed or secured at one end to a projecton 18 attached to the tube 14 by means of a screw 19. The outer extremity of the bimetallic element is adjustably secured to a rod 20 by means of a bracket 21 mounted on the rod 20 and a screw 22 attaching the bimetallic element 17 to the bracket 21. It is apparent, therefore, that when heat comes in contact with the bimetallic element, the nature of which is so well known that it is not believed necessary to elaborate upon, its expansion causes an axial rotation of the helical element to actuate accordingly the rod 20. Further, it is to be understood, that a cooling of the bimetallic element contracts it and changes its direction of movement in a similar manner and likewise the direction of axial rotation of the rod 20.

The rod 20 is rotatably mounted in the bearing 13 and extends therethrough into the casing 10. Mounted on the end of the rod and in frictional engagement therewith is a clip 23 for carrying the mercury tube contactor switch 24. Within the casing 10 is mounted an insulating terminal block 25 upon which is positioned a plurality of binding posts 26 and to these latter may be connected the lead wires 27 which are connectedto the electrodes sealed in the mercury tube contactor switch 24.

To form the frictional engagement between the rod 20 of the actuating element and the mercury contactor, the rod is provided with a collar 28 rigidly secured thereto in any suitable manner.

A collar-like member 29 is loosely secured on the shaft 20 by means of a nut 30, this member 29 functioning as a support for the contactor clip 23. The left hand end of the member 29 is formed with a socket 31. A spiral spring 32 surrounds the shaft 20 and is confined by the collar 28 and another collar 33, the latter being free to slide longitudinally along the shaft 20 under the pressure of said spring 32 and push said member 29 against the nut 30, whereby said member 29 is gripped between collar 28 and nut 30 and is moved when the rod 20 is rotated.

Positioned above the contactor 24 and projecting into the wall of the casing are two stop or limiting members 34. A pin is rigidly secured to the collar 29 and has a relatively narrow range of travel between the stop members 34 thus limiting the distance through which said contactor may be tilted when actuated by the bimetallic ele- -ment 17.

The action apparent from the foregoing description is that the rotary movement of the rod 20 obtained from the actuating element 1'1, is imparted to the member 29 by reason of the spring 32 pressing the collar 33 against the end of the socketed portion of said member 29 which, in turn, is pressed against the nut 30. When the pin 35 contacts with one of the stop members 34, the movement of the member 29 is arrested. However, the actuating member 20 may continue to move, as it very frequently will, under the influence of the continued rotatable expansion or contraction of the bimetallic element, since the loose collar 33 will slide over the end of the sock- .eted portion of the member 29 and permit the overriding movement of the actuator.

.the rotation of the helical bimetallic element 17 and the rod 20 an immediate change in direction of movement of the contactor 24 will take place notwithstanding the distance the rod 20 has been allowed to rotate past the point at which the contactor was arrested.

An apparently irreconcilable condition exists in the stack inasmuch as the substance given oil from the fire, chiefly carbon, tends to deposit upon the actuating element 1'7. In order to minimize the amount of carbon deposit on the element 17, this invention provides for a helical coil in which each of the convolutions are of the same diameter and are spaced a suilicient distance apart to eliminate the buildimz up of carbon deposits between them. Also in spacing the convolutions a greater distance apart, the angles are greater and the further from a vertical plane these angles are, the less is the tendency toward a building up of the carbon deposits in a vertical relation. Therefore it is apparent that the carbon cannot accumulate between the convolutions and prevent the proper thermal influence upon the actuator as would be the case should the heat not pass therethrough. Further, such a condition would hinder the mechanical function of the actuator.

A further feature of this invention is the means whereby the switch may retain a vertical position regardless of the plane in which the wall of the stackisdisposed. Thisisaccomplishedbymeans of a flange 35 bolted orotherwise secured to the stack wall 15, which former includes a projection 36 integral therewith and having an aperture 37 therethrough. The tube 14 and the actuating element 1'! passes through the aperture 37 into the stack and' is securely held in position by the bolts 38. The aperture 37 is of a frustro-conical shape with its smaller diameter substantially the same as that of the tube. With the smaller diameter of the aperture acting in the manner of a pivot and by meansof adjusting the bolts 38, any degree of tilt may be obtained in order that the switch may be positioned in a vertical plane.

From the foregoing description, it will be understood that my electric switch comprises a helical or coiled bimetallic actuator which is adapted to rotate through a relatively wide range, a contactor switch which is mounted upon a holder or clip that is rotated by this actuator, the holder being adapted to move through a relatively narrow and limited range, and frictional engaging means between the holder and the actuator whereby relative movement between the actuator and the holder may obtain when the rotatable movement of the actuator exceeds a predetermined range. Moreover, that whenever the actuator reverses its direction of movement it immediately causes the holder and thereby the contactor to be tiltably moved in the opposite direction from which it was previously tilted.

While I have herein shown and described one embodiment of my invention, it is to be understood that I do not desire to be limited to this exact structure or the details thereof. Various other forms will be apparent to one skilled in the art and consequently the invention is to be limited only by the scope of the appended claims and the prior art.

1. In a thermostatically operated device, the combination of a tubular member, a rotary member extending through said tubular member, a thermostat coil having its outer end secured to said tubular member and its inner and secured to said rotary member, a support for said tubular member comprising a sleeve in which said tubular member is axially shiftable, said tubular member having an air inlet for the entrance of air to circulate through said member and said thermostat coil.

2. In a thermostatically operated device, the combination of a tubular member, a thermostat coil secured at its outer end to the inner end of said tubular member, a shaft extending through said tubular member and Journalled at its outer end in the outer end of said tubular member, the

inner end of said shaft being secured to the inner end of said thermostat coil, said tubular member having an inlet for the flow of air therethrough and through said thermostat coil, and a supporting sleeve receiving said tubular member.

3. In a thermostatically operated device, the combination of a tubular member having an air inlet at its outer end and open at its inner end, a shaft journalled in the outer end of said tubular member and extending therethrough, a thermostat coil secured at its inner end to said shaft and secured at its outer end to said tubular member in the path of air flow through said tubular member, said tubular member and sleeve being relatively movable to control the flow of air through said tubular member.

4. In a thermostatically operated device, the combination of a tubular member which is free to the flow of air therethrough, a shaft journaled intheouterendofsaidtubularmemberandex- 50 tending axially therethrough, a thermostat coil adjacent to the outlet end of said tubular member, said coil being secured at its outer end to said tubular member and at its inner end to said shaft, a sleeve receiving said tubular member, and an air inlet at the outer end of said tubular member, said tubular member and sleeve being relatively axially movable whereby to adjust the area of said air inlet and thereby the volume of air flow through said tubular member.

5. In a thermostatically operated device, the combination of a tubular member, a shaft journaled in the outer end of said tubular member, a thermostat coil adjacent the inner end of said member, the outer end of said coil being secured to said member, said coil at its inner end being secured to and supporting the inner end of said shaft, said tubular member being opened to the flow of air therethrough and said coil being in the path of the air flowing from said member.

6. In a thermostatically operated device, the combination of a tubular member open at its inner end and having an air inlet, a sleeve receiving said tubular member and arranged to control said air inlet, a shaft journaled in the outer end of said tubular member and extending therethrough, a thermostat coil secured to said shaft and to said tubular member in the path of air flow through said tubular member, said tubular member and said sleeve being movable relative to each other to control the flow of air through said tubular member. I

7. In a thermostatically operated device, the combination of a tubular member open at its inner end and having an air inlet, a sleeve receiving said tubular member and arranged to control said air inlet, a shaft journaled in the outer end of said tubular member and extending therethrough, a thermostat coil secured to said shaft and to said tubular member in the path of air flow through said tubular member, said tubular member and said sleeve being movable relative to each other to control the flow of air through said tubular member, and adjustable means for securing said tubular member and said sleeve in a desired relation.

8. In a thermostatically operated device, the

combination of a tubular member, a rotary member extending through said tubular member, a thermostat coil having its outer end secured to said tubular member and its inner end secured to said rotary member, a support for said tubular member comprising a sleeve in which said tubular member is axially shiftable, said tubular member having an air inlet for the entrance of air to circulate through said member and said thermostat coil, said sleeve adjusting the area of said air inlet when said tubular member is shifted in said sleeve.

9. In a thermostatically operated device, the combination of a tubular member, a thermostat coil secured at its outer end to the inner end of said tubular member, a shaft extending through said tubular member and journalled at its outer end in the outer end of said tubular member, the inner end of said shaft being secured to the inner end of said thermostat coil, said tubular member having an inlet for the flow of air therethrough and through said thermostat coil, and a supporting sleeve receiving said tubular member and cooperable therewith to control the area of said air inlet.

LOUIS A. M. PHELAN. 

